3D-Printed Ear Devices Detect Core Body Temperature

By Caleb Sooknanan ’20

Figure 1. Scientists strive to create wearable smart devices that can detect physiological phenomena in real time. According to a study from UC Berkeley, new ear devices can be 3D printed and used to indicate patients’ true body temperatures.

Healthcare sensors are frequently used to detect skin temperature, but more research is needed to design a device that can pinpoint core body temperature levels and help doctors predict the likelihood of fever, fatigue, and other physiological phenomena. Professor Ali Javey and researchers at the University of California, Berkeley designed a printable smart device that — when placed on a patient’s ear — could track core body temperature. The device was designed so that scientists could analyze temperature readings regardless of the user’s condition or environment.

The researchers printed a stretchable base substrate with liquid metal microchannels, as well as integrated circuit chips to process bodily signals. The researchers inserted an infrared sensor to detect temperature differences, a bone conduction system that prevented hearing limitations, and a Bluetooth module that wirelessly transmitted temperature data to a phone application.

The researchers tested their devices’ environmental effectiveness on a human subject placed in rooms ranging in temperature from 6 to 40degrees Celsius. The researchers recorded the subject’s core body temperature as measured by a custom sensor and a typical sensor, while the subject’s skin temperature and environment temperature were measured separately. Temperature changes from exercise were also analyzed within this study, as the researchers measured temperature values with the sensors on the subject’s left ear during a biking session.

Both sensors detected a constant core body temperature while the rooms’ temperatures were below or near 30degrees Celsius, while the subject’s skin temperature fluctuated at different temperatures. For the exercising test, the subject underwent a steady core body temperature increase of about 0.4degrees Celsius, while the skin temperature rapidly increased by 2.5degrees Celsius before decreasing. Moreover, the 3D-printed sensor was very accurate in recording core body temperature conditions despite environmental changes.

This study showed that a 3D-printed sensor could be used independently of external changes to record a patient’s core body temperature. Limitations of the study included how the sizes of the device and its components were reduced by the printer’s resolution. Nevertheless, this device provides further insight into healthcare treatments and long-term monitoring of a person’s health.